Bearing cage segment configured for use with an installation tool

ABSTRACT

A cage segment for a rolling-element bearing having a plurality of rolling elements includes at least one bridge and first and second plates extending from axial ends of the bridge, sides of the bridge being configured to guide rolling elements. Radially inner or outer edges of each of the bridges include at least one axial channel having channel walls projecting radially and circumferentially from the radial inner or outer edge.

CROSS-REFERENCE

This application is a divisional of U.S. Ser. No. 17/030,630 filed Sep.25, 2020, which claims priority to German patent application no. 10 2019214 953.7 filed on Sep. 30, 2019, the contents of which are fullyincorporated herein by reference.

TECHNOLOGICAL FIELD

The present invention relates to an installation tool for installingrolling elements and a bearing ring and to a bearing cage segmentconfigured to be used with the installation tool.

BACKGROUND

For tapered roller bearing assemblies in turbines, for example, forsupporting a main shaft of a wind turbine, tapered roller bearingsincluding one-part cages are currently used. In turbine applicationswherein the tapered roller bearings are used in a back-to-backarrangement and have a diameter of a plurality of meters, due to thesize of the turbines it is not possible to rotate the turbines toinstall the second tapered roller set of the back-to-back arrangement.The tapered roller bearing that is above in the final assembly hastherefore, up to now, been provided with a cage such that the outer ringcan first be installed, and subsequently the inner ring, including therolling elements that are held by the cage, can be inserted downward bythe narrow diameter. However, with this inverted installation the use ofone-part bearing cages is essential, since without such a bearing cage,or with bearing cages that are comprised of individual gage segments,the rolling elements would fall out during the installation.

The one-part cages ensure a self-retaining function of the taperedrollers during the installation and thus allow an inner ring including atapered roller set to be installed in an inverted position. However,these solid cages are very expensive to manufacture and often requireadditional elements on the bearing inner ring, such as, for example, aspecific surface topography of the guide surfaces, which causesadditional costs. Furthermore, the guiding of a cage on the inner ringor the tapered rollers can be subjected to a sliding contact that canincrease the wear of the bearing.

SUMMARY

It is therefore an aspect of the present disclosure to provide apossibility to use bearings including cage segments for such a turbineapplication.

The installation tool for installing a bearing ring including rollingelements includes a ring that is configured to be disposed on a lateralsurface of the bearing ring. The bearing ring can be a bearing innerring or a bearing outer ring. The ring of the installation tool can beconfigured one-piece or segmented.

The installation tool furthermore includes slider elements that aredistributed uniformly around the ring. The ring includes receptacles forthe slider elements. Here the slider elements can be displaced in anaxial direction with respect to the ring and/or a radial directionrelative to the ring. The number of the slider elements can be the sameas the number of rolling elements. Alternatively, fewer slider elementsthan rolling elements can also be provided. In both cases, all or only apart of the slider elements, for example, every second one, can bedisplaced into the end position.

The receptacles can be produced in any manner, for example, asthrough-openings such as bores, milled holes, or by other productionmethods. From a starting position, into which the installation tool canbe moved and in which the slider elements are not displaced relative tothe ring, the slider elements can be displaced into an end position,wherein the slider elements are completely shifted into the end positionrelative to the ring, for example, completely pushed throughthrough-openings. The slider elements can each be comprised of aprofiled, preferably tubular, section or a pin that can be pushedthrough the through-opening.

A bearing is usually delivered with the outer and inner ring fitted androlling elements and cage segments disposed therebetween. In order toinstall the bearing, the installation tool is placed on the bearing ring(in particular the large diameter of an inner ring) and the sliderelements are moved into their end position. With the installation tool,the bearing ring can now be lifted out from the bearing with the rollingelements and the cage segments, and the two bearing rings can beinstalled separately from each other.

Alternatively the installation tool can be placed on the bearing ring(in particular the large diameter of an inner ring) and the bearing ringcan be individually loaded with a combination of rolling elements andcage segments, and the slider elements can be displaced little by littleinto their final position.

Each rolling element can be equipped with a single cage segment, or acage segment can be provided for a plurality of rolling elements orevery second rolling element can be preferably disposed in a pocket of acage segment, wherein walls or bridges of the cage segment are eachdisposed between two rolling elements. Furthermore, the cage segmentscan be configured as spacers between the rolling elements.

In these cases, an assembly of the bearing ring, including the rollingelements, and the cage segments is formed by the installation tool,which assembly can be moved as a whole, in particular placed on a hubunit, without the rolling elements falling downward from the bearingring. For this purpose the slider elements are configured to each bedisposed in the end position between two rolling elements and a contactsurface of a wall of a cage segment, which wall is disposed between thetwo rolling elements. Due to this arrangement of the slider elements aradial mobility of the rolling elements with respect to the bearing ringcan be limited. Here the slider elements assume the function of abearing cage, so that the rolling elements are secured between theslider elements and the bearing ring. The use of a one-part bearing cagecan thus be omitted. Instead, individual cage segments can be used, intowhich the slider elements engage. Such cage segments can each receiveone or even a plurality of rolling elements. Furthermore, the cagesegments can be configured as spacers, between the rolling elements,that do not completely enclose the rollers.

In this way a compact module can be formed from the bearing ring,including the rolling elements and the cage segments, as well as theinstallation tool. This module can then be inserted as a whole, forexample, into an outer ring. The module made of the bearing ring,rolling elements, cage segments, and installation tool can then beinserted into a bearing assembly, or also removed again therefrom.

If the bearing ring is the bearing inner ring, according to oneembodiment the slider elements are disposed, in their end position, inthe free space radially outside the pitch circle diameter between tworolling elements, the contact surface of the cage segment, and theraceway of the outer ring. Alternatively, the bearing ring can be theouter ring, wherein the slider elements are then disposed, in their endposition, in the free space radially inside the pitch circle diameterbetween two rolling elements, the contact surface of the cage segment,and the raceway of the inner ring. Due to this arrangement it can beensured that the rolling elements cannot be removed from the inner ringor the outer ring.

According to a further embodiment, the slider elements are displaceableangularly with respect to the ring surface. In this case, in their endposition the slider elements form a truncated cone shape, wherein thistruncated cone shape is oriented towards the truncated cone shape thatis formed by the roller axes. The diameter of the circle that is formedby the slider elements in their initial position is thus larger than thediameter of the circle that is formed by the slider elements in theirend position, or vice versa.

According to a further embodiment, the installation tool includes acentering element in order to center the ring on the outer diameter of aguide flange of the bearing ring. Due to the centering element an exactradial position of the installation tool with respect to the bearingring can thus be ensured.

According to a further embodiment the installation tool includes anattachment element in order to attach the ring to the bearing ring. Suchan attachment means can be configured, for example, as a clamping orscrew device. Due to such an attachment means a securing of theinstallation tool to the bearing ring can be ensured. Furthermore, thering can be attached to the bearing ring in a rotating manner. For thispurpose rollers can be provided, for example, that make possible arotation of the ring with respect to the bearing ring.

According to a further embodiment the installation tool includes aspacing means for adjusting an axial spacing between the ring and thebearing ring, and/or a spacing means for adjusting a radial spacingbetween the slider elements and the raceways of the rolling elements.The spacing means can be configured, for example, as adjustable spacingmeans, so that the axial spacing between the ring and the bearing ringand/or the radial spacing between the slider elements and the raceway ofthe rolling elements is variably adjusted. In this way the installationtool can be used for various sizes of rolling elements.

According to a further embodiment the installation tool includes aretaining element in order to hold the slider elements in their initialposition and/or end position and/or in one or more intermediatepositions. Such a retaining means can be configured as a lockingelement. For example, the retaining element can be a pin or lever thatcan be moved via a retaining plate of the slider elements in order tohold the slider elements in their upper or lower, i.e., initial or endposition. Alternatively the retaining means can be a clamping device,screw device, or the like. The retaining means can be configured, forexample, as a spring-loaded bolt. Due to such a retaining means it canbe ensured that the slider elements are not displaced unintentionallyfrom their initial position into their end position, or vice versa.

According to a further embodiment the ring is manufactured from a metaland/or the slider elements are manufactured from a plastic or a metal.If the slider elements are produced from a plastic, they can be slightlyelastic, whereby a further adapting to the rolling elements or to aradial clearance or circumferential clearance of the rolling elements ispossible.

According to a further aspect, a cage segment for a rolling-elementbearing is disclosed, wherein the cage segment includes at least onebridge or a plurality of bridges connected via connection plates,wherein the bridge/the bridges includes at least one guide surface forguiding the rolling elements in the installed rolling-element bearing.Here in the installed rolling-element bearing the rolling elements arein contact with the guide surfaces, or are spaced from them by a smallspacing. The cage segment preferably includes two bridges, wherein apocket is formed between the two bridges, in which pocket a rollingelement can be received. With the use of such a cage segment, everysecond rolling element is received in a pocket. Alternatively the cagesegment can be a pure spacer that is disposed between two rollingelements.

In order to make possible an interaction of the cage segment with aninstallation tool as described above, the bridge provides one or morecontact surfaces for slider elements of such an installation tool. Thesecontact surfaces can be disposed centrally in the axial direction (e.g.,only one single, centrally disposed contact surface) or distributed inthe axial direction (e.g., two axially opposing contact surfaces). Dueto the contact surfaces the installation tool is in engagement with thecage segments and in this way can secure the individual cage segments,and thus the rolling elements, against the bearing ring. A one-part cagecan thus be dispensed with.

According to one embodiment, the contact surfaces are disposed radiallyoutside and/or radially inside the pitch circle diameter of the rollingelements. As is described above, in their end position the sliderelements are disposed in the free space radially outside the pitchcircle diameter between two rolling elements, the contact surface of thecage segment, and the raceway of the outer ring, or in the free spaceradially inside the pitch circle diameter between two rolling elements,the contact surface of the cage segment, and the raceway of the innerring. In order to make possible an interaction of the slider elementswith the cage segments, the contact surfaces are therefore also disposedradially outside or radially inside the pitch circle diameter of therolling elements. The guide surfaces also then may comprise the rollingelements, accordingly outside or inside the pitch circle diameter. Thecontact surfaces are preferably disposed both radially inside andradially outside the pitch circle diameter of the rolling elements,since in this way the cage segments can be used flexibly for theinstallation of both the bearing inner ring and the bearing outer ring.

According to a further embodiment, the contact surfaces are configuredas a recess open toward the outer ring and/or the inner ring, whichrecess is elongated in the circumferential direction. Due to acircumferential clearance of the rolling elements and of the cagesegments, an offset of the cage segments with respect to the sliderelements can arise. However, since the contact surfaces have acircumferential extension, the slider elements can also be pushed intothe contact surfaces even in the event of an offset of the cagesegments. Due to the circumferential extension of the contact surfaces,there is no need to make the slider elements be displaceable in thecircumferential direction. However, in order to facilitate installationof the installation tool or of the slider elements, a displacementpossibility can be provided of the slider elements relative to the ringin the circumferential direction.

The contact surfaces can have a circumferential width that ensures acircumferential clearance of the slider element relative to the contactsurface. The circumferential clearance of the rolling elementspreferably corresponds to 0.5 to 1.5 times the circumferential clearanceof the rolling elements.

In order to ensure that the cage segments cannot be arbitrarilydisplaced circumferentially with respect to the slider elements, or thecage segments lose the contact to the slider elements, the contactsurfaces can include a stop in the circumferential direction. This stopcan be provided in both circumferential directions. Due to the stop, themovement of the slider elements is limited in the circumferentialdirection as soon as they are pushed into the cage segments.

According to another aspect, a cage segment for a rolling-elementbearing having a plurality of rolling elements comprises at least onebridge having a first end and a second end spaced in an axial directionand a first side and a second side spaced in a circumferential directionand an outer edge and an inner edge spaced in a radial direction, thecage segment further including a first plate extending perpendicularlyfrom the first end of the at least one bridge and a second plateextending perpendicularly from the second end of the at least onebridge. The first side is configured to contact a first rolling elementof the plurality of rolling elements and the second side is configuredto contact a second rolling element of the plurality of rolling elementsand maintain a spacing between the first and second rolling elements.Also, the radial inner or outer edge includes at least one axial channelhaving channel walls projecting radially and circumferentially from theradial outer edge.

According to another aspect a cage segment for a rolling-element bearinghaving a plurality of rollers includes a first bridge and a secondbridge, each of the first and second bridges having a first end and asecond end spaced in an axial direction and a first side and a secondside spaced in a circumferential direction and an outer edge and aninner edge spaced in a radial direction, the segment further including afirst plate connecting the first end of the first bridge to the firstend of the second bridge and a second plate connecting the second end ofthe first bridge to the second end of the second bridge. The second sideof the first bridge and the first side of the second bridge define apocket for receiving one of the plurality of rollers, and the radialouter edge includes at least one axial channel having channel wallsprojecting radially and circumferentially from the radial outer edge.Outer surfaces of the channel walls are curved to form guide surfacesfor the plurality of rollers, and bottoms of the channels are radiallyspaced from the outer edges of the cage segments.

According to a further aspect, a method is proposed for installing abearing including an inner ring and an outer ring. The method includesthe steps: positioning of the inner ring, positioning of the rollingelements and cage segments on the inner ring, positioning of theabove-described installation tool on the inner ring, displacing of theslider elements of the installation tool into their respective endposition, so that the slider elements are each disposed between tworolling elements and against a contact surface of a wall of a cagesegment, which wall is disposed between the two rolling elements, inorder to limit a radial mobility of the rolling elements with respect tothe bearing ring (i.e., to prevent a falling-out of the rollingelements), inserting of the inner ring including the installation tooland the rolling elements onto a sleeve or shaft and/or into the outerring, and removal of the installation tool. The sleeve or shaft can inparticular be an element of a hub unit of a turbine.

In order to again remove the inner ring from the sleeve or shaft, theinstallation tool can be attached again to the inner ring, and theslider elements can be displaced in order to hold the rolling elementsagainst the inner ring. The inner ring together with the rollingelements and the installation tool can then be removed.

Due to the use of the installation tool it is possible to avoid using aone-part cage, since the slider elements assume the function of abearing cage, so that the rolling elements are secured between theslider elements and the bearing ring. The bearing can therefore be usedwith individual cage segments, into which the slider elements of theinstallation tool engage. Due to such an installation method it istherefore possible to move a bearing ring as a whole, including therolling elements, without a one-part cage. This is required inparticular for applications including large rolling-element bearings,such as, for example, for turbines, as is described above.

According to a further aspect, a bearing is proposed including an innerring and an outer ring, between which rolling elements are disposed thatare held by cage segments. The bearing can be installed in particular bythe above-described installation method.

According to a further aspect, a hub unit for a turbine is disclosedincluding two tapered roller bearings that are disposed in aback-to-back arrangement, wherein the tapered roller bearings eachinclude an inner ring and an outer ring, between which inner ring andouter ring tapered rollers are respectively disposed that are held bycage segments. At least one of the tapered roller bearings can beinstalled by the installation method described above, whereby noone-part cage is required. Instead, the bearing including cage segmentscan be used, as is described in more detail above.

Further advantages and advantageous embodiments are specified in thedescription, the drawings, and the claims. Here in particular thecombinations of features specified in the description and in thedrawings are purely exemplary, so that the features can also be presentindividually or combined in other ways.

In the following the invention shall be described in more detail usingexemplary embodiments depicted in the drawings. Here the exemplaryembodiments and the combinations shown in the exemplary embodiments arepurely exemplary and are not intended to define the scope of theinvention. This scope is defined solely by the pending claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an installation tool according to anembodiment of the present disclosure

FIG. 2 is a perspective detail view of a cage segment for use with theinstallation tool of FIG. 1 .

FIG. 3 is a perspective view of an arrangement of the installation tooland of a bearing ring.

FIG. 4 is a further perspective view of an arrangement of theinstallation tool and of a bearing ring.

FIG. 5 is a sectional view of a hub unit of a turbine with aninstallation tool according to the present disclosure attached.

FIG. 6 is a sectional view of the hub unit of FIG. 5 with the bearinginner ring installed.

FIG. 7 is a perspective view of the detail of the hub unit of FIG. 5including pulled-out slider elements.

DETAILED DESCRIPTION

In the following, identical or functionally equivalent elements aredesignated by the same reference numbers.

FIG. 1 shows a perspective view of an installation tool 1. Theinstallation tool 1 includes a ring 2. Through-openings 4 are providedin the ring 2 through which slider elements 6 can be pushed. The sliderelements 6 are comprised of a first tubular (or cylindrical) section 8that is pushed through the through-openings 4, a retaining grip 10, anda second tubular (or cylindrical) section 12 to which the retaining grip10 is attached. The second tubular section 12 preferably has a largerdiameter than the through-openings 4, so that the insertion depth of theslider elements 6 is thereby limited. The end position of the sliderelements 6 is thereby defined by contact between the second tubularsection and the ring 2.

In order to attach the installation tool 1 to a bearing ring, the ring 2includes a centering means 14. The centering means 14, which isconfigured as an edge (or shoulder), serves to arrange the installationtool 1 on the bearing ring, the centering means 14 abutting against anouter side of the bearing ring, for example, a guide flange.

Although in the Figures the installation tool is configured such that itis arrangeable on an inner ring of a bearing, the installation tool 1can also be configured such that it can be connected to an outer ring ofa bearing.

If the installation tool 1 is disposed on a bearing ring, it interactswith a cage segment 16 as is depicted in FIG. 2 . Such a cage segment 16includes two bridges 18 that are connected at their respective ends to aconnecting or base plate 20. Between the bridges 18 and the connectingplates 20, a pocket 22 for receiving a rolling element, in particular atapered roller, is respectively formed. With the cage segments 16 shownhere, for example, each second rolling element can be received in such acage segment.

In order to be able to bring the slider elements into contact with thecage segments 16, the cage segments 16 include contact surfaces 24.These contact surfaces 24 each have an extension L in thecircumferential direction, each of which extension L is bounded by astop surface 26. The stop surface 26 serves to hold the slider elementsinside the contact surface 24. Due to the extension L it is possible tocompensate for a clearance of the rolling elements for the sliderelements 6, since the slider elements 6 can move between the two stopsurfaces. The contact surfaces 24 include guide surfaces 28 curvedtoward the rolling elements. The rolling elements can abut againstthese.

FIGS. 3 and 4 show perspective views of an installation tool 1 that isdisposed on a bearing ring 30. In this case the bearing ring 30 is aninner ring of a bearing. The inner ring 30 is provided with rollingelements 32. In the exemplary embodiment shown in FIG. 3 , theinstallation tool 1 is disposed on the bearing ring 30, wherein theslider elements 6 are located in their initial position. In FIG. 4 theslider elements 6 are located in their end position. As can be seenhere, in their end position the slider elements 6 are each disposedbetween two rolling elements 32 of the bearing ring 30. The rollingelements 32 are spaced by cage segments 16. As described above, the cagesegments 16 are configured such that a cage-type segment 16 is disposedaround every second rolling element 32, wherein a base plate 20 connectstwo walls or bridges 18 of the cage segment 16. As shown in FIG. 3 , thecentering means 14 of the installation tool 1 abuts against a guideflange 33 of the inner ring 30.

In their end position the slider elements 6 are disposed over a pitchcircle diameter of the rolling elements 32 and are in contact with thecontact surfaces 24 of the cage segments 16. In this way the sliderelements 6 are configured to hold the rolling elements 32 against thebearing ring 30 in their end position. Due to the use of theinstallation tool 1, it is possible to dispense with a one-part cage andinstead use cage segments 16 as shown here. Since the installation tool1 assumes the function of a cage and secures the rolling elements 32against the bearing ring 30, it is possible to move the bearing ring 30with the rolling elements 32 without the rolling elements 32 fallingout.

An installation process of a bearing ring 30 using the installation tool1 is now described with reference to FIGS. 5 to 7 .

The installation shown here of the bearing ring 30 is the installationof an inner ring 30 onto a sleeve or shaft of a hub unit 34 of aturbine. The hub unit 34 includes two tapered roller bearings 36, 38that are disposed in a back-to-back arrangement. Here the tapered rollerbearings 36, 38 are only installed onto the hub unit 34 from one side,namely from the side of the tapered roller bearing 38 outward.

The tapered roller bearing 36 includes an inner ring 40 that is pushedonto the sleeve or shaft 42. During the installation of the taperedroller bearing 36, the rolling elements 44 can be easily arranged on theinner ring 40, since due to the back-to-back arrangement the rollingelements 44 cannot fall downward. An outer ring 46 is then attached tothe rolling-element bearing 36. A housing 48 can then be attached inorder to protect the bearing.

In order to now install the bearing 38, it is necessary to rotate thehub unit 34, which is difficult to carry out due to the size of the hubunit 34 of a plurality of meters. Alternatively the bearing 38 also mustalso be installed from above, like the bearing 36. However, since therolling elements 32 cannot be attached to the bearing inner ring 30 inorder to insert the bearing ring 30 into the outer ring 50, since inthis case due to the force of gravity the rolling elements would fallout, it has been necessary up to now to use a one-part cage in order tohold the rolling elements 32 against the bearing ring 30. However, thiscan be avoided due to the installation tool 1.

As shown in FIGS. 5 to 7 , the installation tool 1 is placed on thebearing ring 30, and the slider elements 6 are displaced into their endposition. Due to this positioning of the installation tool 1, therolling elements 32 are held against the bearing ring 30, as isdescribed with reference to FIGS. 1 to 4 . This module, comprised of theinstallation tool 1, the bearing inner ring 30, the cage segments 16,and the rolling elements 32, can now be easily pushed onto the sleeve42. The bearing outer ring 50 can thereby already be disposed, asdepicted in FIG. 5 .

As shown in FIG. 6 , the bearing inner ring 30 can be pushed onto sleeve42 as a compact module including the rolling elements 32 and theinstallation tool 1.

As soon as the bearing rings 30, 50 and the rolling elements 32 arecorrectly positioned, the installation tool 1 can be removed again. Thisis depicted in FIG. 7 , wherein it is shown how the slider elements 6are pulled out from the assembled bearing assembly. After the pullingout of the slider elements 6, the installation tool 1 can be removedagain in a simple manner.

Due to the installation tool shown here a simple installation of abearing ring including rolling elements is possible without the use of aone-part cage.

Representative, non-limiting examples of the present invention weredescribed above in detail with reference to the attached drawings. Thisdetailed description is merely intended to teach a person of skill inthe art further details for practicing preferred aspects of the presentteachings and is not intended to limit the scope of the invention.Furthermore, each of the additional features and teachings disclosedabove may be utilized separately or in conjunction with other featuresand teachings to provide improved bearing installation tools.

Moreover, combinations of features and steps disclosed in the abovedetailed description may not be necessary to practice the invention inthe broadest sense, and are instead taught merely to particularlydescribe representative examples of the invention. Furthermore, variousfeatures of the above-described representative examples, as well as thevarious independent and dependent claims below, may be combined in waysthat are not specifically and explicitly enumerated in order to provideadditional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intendedto be disclosed separately and independently from each other for thepurpose of original written disclosure, as well as for the purpose ofrestricting the claimed subject matter, independent of the compositionsof the features in the embodiments and/or the claims. In addition, allvalue ranges or indications of groups of entities are intended todisclose every possible intermediate value or intermediate entity forthe purpose of original written disclosure, as well as for the purposeof restricting the claimed subject matter.

REFERENCE NUMBER LIST

-   1 Installation tool-   2 Ring-   4 Through-opening/receptacle-   6 Slider element-   8 First tubular section-   10 Retaining grip-   12 Second tubular section-   14 Centering means-   16 Cage segment-   18 Bridge-   20 Connecting/base plate-   22 Pocket-   24 Contact surface-   26 Stop-   28 Guide surface-   30 Inner ring-   32 Rolling element-   33 Guide flange-   34 Hub unit-   36 Tapered roller bearing-   38 Tapered roller bearing-   40 Inner ring-   42 Sleeve/shaft-   44 Rolling element-   46 Outer ring-   48 Housing-   50 Outer ring-   L Extension

What is claimed is:
 1. A cage segment for a rolling-element bearinghaving a plurality of rolling elements, the cage segment comprising: afirst bridge and a second bridge each having a first end and a secondend spaced in an axial direction and a first side and a second sidespaced in a circumferential direction and an outer edge and an inneredge spaced in a radial direction, and a first plate extendingperpendicularly from the first end of the first bridge to the first endof the second bridge and a second plate extending perpendicularly fromthe second end of the first bridge to the second end of the secondbridge, wherein the first side of the first bridge is configured tocontact a first rolling element of the plurality of rolling elements andthe second side of the first bridge is configured to contact a secondrolling element of the plurality of rolling elements and maintain aspacing between the first and second rolling elements, wherein the firstside of the first bridge defines a first circumferential end of the cagesegment and the second side of the second bridge defines a secondcircumferential end of the cage segment, and wherein the radial outeredge of the first bridge and the radial outer edge of the second bridgeeach include at least one axial channel having channel walls or whereinthe radially inner edge of the first bridge and the radial inner edge ofthe second bridge each include at least one axial channel having channelwalls.
 2. The cage segment according to claim 1, wherein the firstbridge and the second bridge define a pocket for receiving the secondrolling element.
 3. The cage segment according to claim 2, wherein theat least one axial channel comprises a first axial channel axiallyspaced from a second axial channel.
 4. The cage segment according toclaim 3, wherein outer surfaces of the channel walls define guidesurfaces for the plurality of rolling elements.
 5. The cage segmentaccording to claim 4, wherein the rolling elements are rollers.
 6. Thecage segment according to claim 3, wherein the at least one axialchannel is substantially U-shaped.
 7. The cage segment according toclaim 4, wherein a spacing from the outer surface of the channel wall ofthe first bridge to the outer surface of the channel wall of the secondbridge is less than a spacing between the first bridge and the secondbridge.
 8. An assembly comprising: a plurality of the cage segmentaccording to claim 2 and the first rolling element and the secondrolling element.
 9. The cage segment according to claim 1, wherein thechannel walls project radially from the radial outer edge or the channelwalls project radially from the radially inner edge.
 10. The cagesegment according to claim 1, wherein the channel walls project radiallyfrom the radial outer edge.
 11. The cage segment according to claim 1,wherein the channel walls project radially and circumferentially fromthe radial outer edge or the channel walls project radially andcircumferentially from the radially inner edge.
 12. The cage segmentaccording to claim 1, wherein the channel walls project radially andcircumferentially from the radial outer edge.
 13. The cage segmentaccording to claim 1, wherein the first side of the second bridge isconfigured to contact the second rolling element of the plurality ofrolling elements.
 14. The cage segment according to claim 1, wherein thechannel walls of the at least one axial channel of the first bridgeinclude a first channel wall circumferentially spaced from a secondchannel wall, wherein the first channel wall extends in a directioncircumferentially away from the second bridge and the second channelwall extends in a direction circumferentially toward the second bridge.15. The cage segment according to claim 14, wherein the first side ofthe second bridge is configured to contact the second rolling element ofthe plurality of rolling elements.
 16. The cage segment according toclaim 15, wherein the first channel wall includes a curved side facingaway from the second bridge configured to guide the first rollingelement of the plurality of rolling elements.
 17. A cage segment for arolling-element bearing having a plurality of rollers, the cage segmentcomprising: a first bridge and a second bridge, each of the first andsecond bridges having a first end and a second end spaced in an axialdirection and a first side and a second side spaced in a circumferentialdirection and an outer edge and an inner edge spaced in a radialdirection, and a first plate connecting the first end of the firstbridge to the first end of the second bridge and a second plateconnecting the second end of the first bridge to the second end of thesecond bridge, wherein the first side of the first bridge defines afirst circumferential end of the cage segment and the second side of thesecond bridge defines a second circumferential end of the cage segment,wherein the second side of the first bridge and the first side of thesecond bridge define a pocket for receiving one of the plurality ofrollers, wherein each radial outer edge includes a pair of wallsprojecting radially and circumferentially from the radial outer edge,facing inner surfaces of each pair of walls defining a channel and outersurfaces of each pair of walls being curved to form guide surfaces forthe plurality of rollers, and wherein bottoms of the channels areradially spaced from the outer edges of the cage segments.
 18. The cagesegment according to claim 17, wherein the at least one channelcomprises a first channel axially spaced from a second channel.
 19. Anassembly comprising the cage segment according to claim 18 and a rollerin the pocket.